Rollup merge of #93217 - willcrichton:example-analyzer, r=GuillaumeGomez

Rollup merge of #93217 - willcrichton:example-analyzer, r=GuillaumeGomez

Improve Rustdoc UI for scraped examples with multiline arguments, fix overflow in line numbers

This PR improves a few aspects of the scrape examples feature in Rustdoc.
* Only function names and not the full call expression are highlighted.
* For call-sites with multiline arguments, the minimized code viewer will scroll to the top of the call-site rather than the middle if the argument is larger than the viewer size, ensuring that the function name is visible.
* This fixes an issue where the line numbers column had a visible x-scroll bar.

r? `@GuillaumeGomez`